(: 
Part 2 / Q4
The QID of questions from the question bank that are not on the quiz. 
:)

let $bank := fn:doc("bank.xml")/QuestionBank/Question/*/@QID
let $quiz := fn:doc("quiz.xml")/Quiz/Question/@QID

for $bQID in $bank
where every $qQID in $quiz satisfies $bQID ne $qQID
return ($bQID)
